Allyson Felix of the United States finished in 21.88 seconds to win the gold medal. Carmelita Jeter, another American, ran in 22.14 seconds to take bronze.
"She's had a very good season and definitely deserves this moment," Richards-Ross, who finished fifth in 22.39 seconds, told The Associated Press of her teammate. "She's just like me -- she's wanted this for a very long time."
Ross told the Jaguars' official website that he knew Richards-Ross was disappointed with the outcome, but he was "really proud of her." Richards-Ross will have a chance at another medal this weekend when she runs in the 4x400 relay.
The Associated Press contributed to this report.